When sensing pressure in aerospace or other commercial systems, it is often necessary to isolate the process fluid (e.g., fuel) from the electronic sensing elements on the pressure sensor. The usual practice for doing so consists of employing a thin corrugated metal barrier that covers a cavity that houses the pressure sensor electronic sensing elements. This cavity is then filled will inert oil and sealed, providing a means to couple the process-fluid pressure to the sensor, but at the same time isolating the sensor from the process fluid itself.
Process fluids can be chemically destructive to the sensing element or be conductive, which provides unwanted current leakage in the sensor elements. The described isolators introduce non-correctable errors that increase approximately to the diameter ratio to the third power as the diameter of the isolator is decreased. Additionally, the oil fill has limitations with temperature swing; most oil fills that work at higher temperatures are gels at cold temperatures. In addition, the oil fill presents an additional failure mechanism; if the oil leaks out of the sensor, the sensor can no longer measure pressure and fails.